Bolt with collar and flexible sleeve insert

ABSTRACT

A fastening device for cooperating with a shaft, wherein the fastening device includes: a deformable sleeve, and a locking collar, the deformable sleeve is configured to have a perimeter relative to the shaft such that the deformable sleeve can be pushed over the shaft, and the locking collar is configured to push over the sleeve so as to bear against a surface of the sleeve and to cause the fastening device to engage with the shaft.

TECHNICAL FIELD

This invention relates to a friction mechanism.

More specifically, the present invention relates to friction mechanismswhich are variations on fastener mechanisms.

BACKGROUND ART

Shafts of one form or another are commonly used to hold one or morearticles in place as part of an assembly. The shaft is passed throughthe article and a fastener used to hold the article in place on theshaft.

A very common example is a shaft in the form of a threaded bolt. Thearticles to be assembled are loaded onto the bolt, and a fastener, inthe form of a threaded nut, is wound onto the shaft and tightenedagainst the article such that the article is secured between a bearingsurface on the head of the bolt and a bearing surface on the nut.

There are, however, a number of well known problems with the use of nutsas fasteners on bolts. These include:

-   -   The need to align the threads of the nut and bolt in order to        engage the nut onto the bolt. This is time consuming and if not        done properly may lead to cross-threading which essentially        destroys and integrity of the threads on either the nut or the        bolt (or both), resulting in both having to be discarded.    -   Typically a large number of rotations of the nut (or bolt) are        required to move the nut along the shaft of the bolt prior to        tightening. This is time consuming, particularly in situations        where the bolt extends a significant amount from where the nut        is to be engaged with the article to be fastened.    -   There may be limited access available to the nut and bolt making        it difficult to engage a tool to turn the nut or bolt.    -   Typically only a small fraction of the available thread on the        nut is used to hold the nut in position when tightened. As a        consequence there may be little resistance to the nut loosening        as may occur for example due to vibration. Loosening of nuts as        a result of vibration may constitute a critical safety factor in        many assemblies.    -   In all cases there is a limit to the torque that may be applied        to tighten a nut before damage occurs to the threads. If this        limit is exceeded the result generally is deformation of the        threads to a point where the thread is stripped, either from the        nut or bolt. In such cases the nut and bolt must be replaced        which may be costly and time consuming.    -   These problems have created a high demand for a fastener that        can be quickly located onto a shaft and securely held thereto.

Roopnarine, in U.S. Pat. No. 6,712,574 discloses a quick insertionfastener comprising a casing in which a plurality of inserts is held bya variety of springs and retainers. The inserts are arranged such thatthey are spaced away from the shaft of a bolt when inserted, and engagewith the threads of the bolt on rotation of the casing.

This device, and the many other similar ones, for example Fiorell et alin U.S. Pat. No. 5,988,965, all require a complex arrangement of manypieces, each of which must be configured to fit into the casing and tocooperate with each other both when retained and when engaged. Thesedevices may therefore not only be costly to manufacture but the piecesmust also be carefully assembled prior to use, adding further to thecost of the fastener.

Furthermore, there is always the possibility of jamming of the parts, orof foreign matter entering the mechanism, either of which may lead tofailure of the fastener to operate.

A common feature among these prior art fasteners (and similar ones) isthat they are adapted to engage with a threaded shaft. The threadedcomponents of the devices are required in order to tighten the deviceagainst a bearing surface (such as an object on the shaft or the head ofa bolt) on the shaft. These fasteners still depend on rotation to engagecomplementary screw threads in the same manner as a nut and bolt, andtherefore may suffer from the problems outlined above when tightened.

It is an object of the present invention to address the foregoingproblems or at least to provide the public with a useful choice.

All references, including any patents or patent applications cited inthis specification are hereby incorporated by reference. No admission ismade that any reference constitutes prior art. The discussion of thereferences states what their authors assert, and the applicants reservethe right to challenge the accuracy and pertinency of the citeddocuments. It will be clearly understood that, although a number ofprior art publications are referred to herein, this reference does notconstitute an admission that any of these documents form part of thecommon general knowledge in the art, in New Zealand or in any othercountry.

It is acknowledged that the term ‘comprise’ may, under varyingjurisdictions, be attributed with either an exclusive or an inclusivemeaning. For the purpose of this specification, and unless otherwisenoted, the term ‘comprise’ shall have an inclusive meaning—i.e. that itwill be taken to mean an inclusion of not only the listed components itdirectly references, but also other non-specified components orelements. This rationale will also be used when the term ‘comprised’ or‘comprising’ is used in relation to one or more steps in a method orprocess.

Further aspects and advantages of the present invention will becomeapparent from the ensuing description which is given by way of exampleonly.

DISCLOSURE OF INVENTION

According to one aspect of the invention there is provided a fasteningdevice for cooperating with a shaft, wherein the fastening deviceincludes

a deformable sleeve, anda locking collar,characterised in thatthe deformable sleeve is configured to have a perimeter relative to theshaft such that the deformable sleeve can be pushed over the shaft, andthe locking collar is configured to push over the sleeve so as to bearagainst a surface of the sleeve and to cause the fastening device toengage with the shaft.

According to another aspect of the invention there is provided a kit setincluding

a deformable sleeve,a locking collar, anda shaftwherein the deformable sleeve is configured to have a perimeter relativeto the shaft such that the deformable sleeve can be pushed over theshaft, andthe locking nut is configured to push over the sleeve so as to bearagainst a surface of the sleeve and to cause the fastening device toengage with the shaft.

According to another aspect of the invention there is provided a methodof using a fastening device in relation to a shaft, the fastening deviceincluding a deformable sleeve and a locking collar,

characterised by the steps of

-   -   a) pushing the deformable sleeve into position along the shaft,        and    -   b) pushing the locking collar along the shaft and over the        deformable sleeve, so that a surface of the locking collar bears        against a surface of the deformable sleeve, and    -   c) pushing the locking collar further over the deformable sleeve        until a surface of the deformable sleeve fastens to the shaft.

According to another aspect of the invention there is provided a methodof using a fastening device in relation to a shaft, the fastening deviceincluding a deformable sleeve and a locking collar,

characterised by the steps of

-   -   a) forming a fastening device by pushing the deformable sleeve        partially into the locking collar until the sleeve is held by        the collar, and    -   b) pushing the fastening device into position along the shaft,        and    -   c) pushing the locking collar further over the deformable sleeve        until a surface of the deformable sleeve fastens to the shaft.

It is envisaged that the principles behind the fastening device of thepresent invention can be applied to fastening devices in a wide varietyof shapes and sizes and for use in a variety of situations. For ease ofreference the fastening device shall be referred to as a sleeve clamp.It should be appreciated however that this is not intended to belimiting.

A sleeve clamp according to the current invention is a device that maybe pushed onto a shaft and fastened to the shaft at some position.

In all embodiments the initial movement to locate and secure a sleeveclamp to a shaft is a push.

However, it should be appreciated that in some embodiments the sleeveclamp, or a component of it, may be rotated after it has been pushedonto and fastened to the shaft. This may be done, for example, toprovide additional grip between the sleeve clamp and the shaft.

In some embodiments the sleeve clamp may include a collar configured topush and rotate over a sleeve in order for the collar to bear against asurface of a sleeve. For example, a push and turn motion (e.g., helical)may be required for engagement of cooperating details of the sleeveclamp, as outlined in more detail below.

In some embodiments, to be discussed in more detail below, a sleeveclamp may include internally threaded components, or be configured toengage with a threaded shaft, in which case some rotation of the clamp,or a component of it, may be required.

Reference to a shaft throughout this specification should be understoodto refer to a rigid elongate solid or hollow rod. Commonly a shaft maybe a straight rod of circular cross-section, such as a uniform solid orhollow cylinder.

However, it will be apparent that a shaft for use with the presentinvention may have any suitable cross-section and indeed thecross-section may vary along the length of the shaft.

In some embodiments the sleeve clamp may be configured to cooperate witha shaft having a non-circular cross section.

An advantage of using a sleeve clamp with a shaft having a non-circularcross section is that the non-circularity hinders rotation of thefastener with respect to the shaft. This may be particularly importantfor uses in which the shaft and fastener are subject to vibration, acommon cause of failure of fasteners involving threaded nuts and boltswhich by necessity must have a circular cross section.

The outer surface of the shaft may be adapted in many ways to suitdifferent embodiments of the present invention. For example the outersurface may in some cases be smooth, roughened, or may be threaded ormodified in some other way to enhance the action of the sleeve clamp.

Reference to a sleeve throughout this specification should be understoodto refer to an object configured such that it at least partiallyencloses a shaft inserted into it.

A sleeve according to the present invention has a perimeter that enablesthe sleeve fit around a shaft with sufficient clearance to pass freelyalong the shaft.

In all embodiments a sleeve has an outer surface and a hollow corebounded by an inner surface.

In a preferred embodiment the sleeve clamp includes a single sleeve only

Use of a single sleeve only overcomes many of the problems of prior artdevices that are formed from a plurality of parts.

A single sleeve may be configured to be self-supporting when pushed ontoa shaft. This obviates the need for the complex arrangements of springsand other forms of retainers used in prior art devices in order to holdthe multiple components in place and clear of the shaft prior toengagement.

Use of a single sleeve may significantly reduce the amount of machiningrequired as only one piece is formed. In prior art fasteners severalpieces are formed each of which must be configured to cooperate withother components in order to fit into a fastener.

These advantages may lead to substantial savings in the cost ofmanufacture of the fastener, as fewer components are required and thereis no need for pre-assembly.

Use of a single sleeve also reduces the possibility of failure due tomisalignment or jamming of multiple components.

Reference will be made throughout the specification to a sleeve clampincluding a single deformable sleeve only. However, it will beappreciated that any number of deformable sleeves may be used with thecurrent invention and that reference to a single sleeve only should notbe considered limiting.

A deformable sleeve should be understood to mean a sleeve that iscapable of changing shape when subjected to an applied force.

A deformable sleeve may be configured such that when an appropriateforce is applied to the sleeve its shape changes so that the innersurface of the sleeve contacts an outer surface of a shaft to which thesleeve is fitted,

In preferred embodiments the sleeve may deform such that substantiallythe entire inner surface of the sleeve contacts a surface of a shaft towhich it is fitted.

This is an important feature as the grip between a sleeve clamp and ashaft is dependent (among other factors) on the extent of contactbetween the sleeve and the shaft.

It is envisaged that the material from which the sleeve may be made ispreferably of a type and construction that possesses a material“memory”. This means that if the sleeve is deformed through forcesplaced on it, there is a natural tendency for the material “memory” tobias the sleeve back towards its original shape.

Deformation in which the body returns to its original shape followingremoval of the external forces causing the deformation is commonlyreferred to as elastic deformation.

An advantage of using a sleeve that may be elastically deformed is thatfollowing use (deformation) the sleeve returns to its original shape,allowing it to be reused as required without degradation.

A deformable sleeve may be formed from a material that readilycompresses elastically when subjected to an applied force. Examples ofsuch materials include various rubbers and foam plastics.

In other embodiments a deformable sleeve may be formed from a relativelyincompressible material that has been configured to allow deformation tooccur. Examples of such materials include metals and rigid plastics. Asleeve made from such materials may be formed in a manner that allowsall or part of the sleeve to move when a force is applied.

In some embodiments a combination of materials may be used. For examplea composite sleeve may be formed having a relatively incompressibleouter layer and a relatively compressible inner layer. The outer layermay be configured to deform under an applied force, thus compressing theinner layer.

Such a sleeve may be of advantage in situations where there is arequirement to limit damage to a shaft. An example may be a sleeve clampused as a splint or as a way of holding a bandage in place, or in othersituations where the “shaft” is a body part.

Other forms of composite sleeves may be formed from materials havingdifferent properties. For example an insert of a relatively compressiblematerial may be included in a sleeve formed primarily from a relativelyincompressible material. The inserts may be placed in a location wherethe required deformation may be greater than can be readily achieved bythe relatively incompressible material.

Alternatively, an insert of relatively incompressible material may beincluded in a sleeve in order to stiffen a region of a relativelycompressible sleeve.

In a preferred embodiment the sleeve includes a slit extending at leastpartially along the length of the sleeve.

A slit in the current specification may be of any shape and size asrequired, a slit generally referring to a region where material has beenremoved from an otherwise continuous sheet or surface. A slit may be inthe form of an opening extending through a sheet of material, or may bein the form of a groove in a surface.

In some embodiments a slit may be a straight. However in otherembodiments a slit may be curved, for example into a helical or spiralform.

Inclusion of a slit in a sleeve is one way in which the ability of thesleeve to deform may be enhanced. A slit provides space for the materialof the sleeve to move into when the sleeve is squeezed by an appliedforce, generally causing the sleeve to deform inwards.

In other embodiments a sleeve may include a plurality of slits.

A plurality of slits may be used to increase the flexibility of a sleeveto deform under an applied force, allowing for more varied and complexshapes to be formed. This may be an advantage in instances where theouter surface of a shaft is non-circular, for example if the shaft has asquare or polygonal shape.

A sleeve clamp according to the present invention includes a lockingcollar configured to push along a shaft and over a sleeve so as to bearagainst a surface of the sleeve.

In a preferred embodiment the locking collar bears against an outersurface of the sleeve.

Reference is made throughout this specification to the locking collarbearing against an outer surface of the sleeve. However, it should beappreciated that the collar, or part of it, may bear against some othersurface of the sleeve, such as the surface of a slit in the sleeve, andthat reference to the collar bearing on an outer surface of the sleeveonly should not be seen as limiting

Reference to a collar should be understood to refer to an objectconfigured so as to restrain and hold in place an enclosed object.

The outer surface of the sleeve and the inner surface of the lockingcollar are configured such that pushing the locking collar over thedeformable sleeve exerts a force on the sleeve, causing the sleeve todeform in a manner that reduces an inner perimeter of the sleeve.

In use in conjunction with a shaft a locking collar is pushed over andalong a deformable sleeve on the shaft, causing the sleeve to deformuntil the sleeve clamp achieves the desired attachment to the shaft.

In most cases this involves substantially the entire inner surface ofthe sleeve contacting the outer surface of the shaft.

A locking collar according to the current invention may therefore berelatively non-deformable in comparison with the deformable sleeve. Arelatively rigid locking collar is required in order to cause the sleeveto deform when the locking collar bears against it.

In a preferred embodiment an inner surface of the collar and an outersurface of the sleeve are tapered.

Reference to a tapered surface should be understood to refer to asurface of an object configured such that one end of the object isnarrower than the other end.

The end of a sleeve or collar at which the tapered surface has thelargest perimeter will be referred to as the base of the sleeve orcollar. The end distal to the base (smaller perimeter) will be referredto as the top.

In a preferred embodiment an inner surface of the collar and an outersurface of the sleeve are frusto-conical.

The outer surface of the sleeve and the inner surface of the collar maybe formed from similar frusto-conical sections, i.e., sections cut fromidentical cones with the apex removed.

Reference will be made throughout this specification to surfaces formedas frusto-conical sections. However, it should be appreciated that otherforms of tapered surface may be used with the current invention,including non-uniformly tapered surfaces, and that reference tofrusto-conical surfaces only should not be seen as limiting.

A collar formed in this manner may be pushed over and along the sleeveuntil the inner surface of the collar is in substantially full contactwith the outer surface of the sleeve. When the collar is pushed furtherit exerts a force on the outer surface of the sleeve, causing the sleeveto deform.

In use the sleeve of a sleeve clamp is moved into position on a shaft.The locking collar is then pushed over the sleeve sufficiently to causean inner surface of the deformed sleeve to contact the outer surface ofthe shaft.

The further the collar is pushed over and along the sleeve the greaterthe force exerted onto the sleeve.

In all embodiments following engagement of the sleeve and locking collarthey are held in place with respect to one another by the reaction forceof the elastically deformed sleeve pushing against the locking collar.

The sleeve clamp is held in position on a shaft by the frictional forceexerted between the inner surface of the deformed sleeve and the outersurface of the shaft.

The frictional force, and hence the grip between the sleeve clamp andthe shaft, is proportional, among other things, to the area of contactbetween the inner surface of the sleeve and outer surface of the shaft,and to the amount of force applied.

Therefore, where an increased grip is required the length of the sleevemay be increased (thus increasing the contact area) or the lockingcollar may be configured to press down with greater force onto thesleeve (or both).

The amount of force exerted by the locking collar onto the sleeve, andhence onto the shaft, may be adjusted by changing the angle of thetapered surfaces.

Generally for a tapered surface the force is greatest for taper anglesof around 45°. It should be appreciated, however, that other factors,such as the ease of moving a collar over a sleeve, may influence thechoice of taper angle for a given application.

In some embodiments the grip may be enhanced by appropriate surfacepreparation, for example by roughening the inner surface of the sleeveand the outer surface of the shaft. The grip between the outer surfaceof the sleeve and the inner surface of the collar may similarly beincreased by roughening the surfaces.

In some embodiments the inner surface of the collar and/or the outersurface of the sleeve may be polished or coated or lubricated to allowthe collar to move more easily over the sleeve.

Different materials may be used in some embodiments of a sleeve clamp inorder to provide other features. For example suitably configuredmaterials of different hardness may be used on contact surfaces, such asthat between a sleeve and a locking collar or between a sleeve and ashaft, in order to provide thread cutting.

In some embodiments the outer surface of the sleeve and the innersurface of the collar may include surface features to provide additionalfunctionality.

Generally the inner surface of a collar may have complementary featuresto those of the outer surface of a sleeve, so that the two surfacescooperate to provide the additional features.

For example the outer surface of the sleeve may include one or moreridges or grooves running around a perimeter of the surface. In thisembodiment the inner surface of the collar may include grooves or ridgesthat correspond to the ridges and grooves respectively on the sleeve.The collar in this embodiment may be pushed over the sleeve until aridge (for example) extending around the inner surface of the collarengages with a groove around the sleeve. At this point the collar“snaps” into a fixed position on the sleeve in what may be termed a“click and hold” position.

A number of grooves around the outer perimeter of the sleeve may be usedto calibrate the connection between the sleeve and the collar as theposition of the grooves along the sleeve determines how much of thesleeve is covered by the collar, and hence how much force is beingexerted onto the sleeve.

In some embodiments a groove and ridge (spline) may extendlongitudinally along the length of the sleeve and/or collar. For examplea longitudinal groove may be formed on the outer surface of a sleeve anda complementary spline formed on the inner surface of a collar (or viceversa). The collar may then be aligned with the sleeve so that thespline engages in the groove. This may be useful in instances where thealignment of the collar and sleeve is important. It also provides a keyfor locking the sleeve to the collar such that rotation of the collarforces the sleeve to rotate.

A flange may be included at the base of a sleeve, the base being thewider end of the tapered sleeve that in use abuts an article to be fixedon a shaft. This may serve to prevent the collar from further movementover the sleeve, as well as to provide an additional area to the surfaceabutting the article to be fixed.

In some embodiments the sleeve may include a “step down” region in whichthe tapered surface near the base ends and is replaced with anon-tapered portion that has a smaller perimeter than the taperedsurface at that point.

The inner surface of a corresponding collar may include a taperedsurface near the base that ends and is replaced with a non-taperedportion that protrudes towards the centre of the collar.

In operation the collar is pushed over the sleeve such that theprotruding non-tapered section of the base of the collar bears againstthe tapered surface of the sleeve. When the non-tapered section of thecollar is pushed over the non-tapered section of the sleeve, the collarsnaps into position against the sleeve so that the tapered andnon-tapered sections of the sleeve and collar respectively bear againstone another.

This arrangement may be useful as a means of applying a predeterminedcoverage (and hence force) of the collar on the sleeve.

The arrangement has the added advantage of providing a lip (between thenon-tapered and tapered regions) which acts as a barrier to movement ofthe collar back over the sleeve, a move that would otherwise allow thesleeve clamp to loosen. The lip could be made large enough to limit thetendency of the collar to slip back on the sleeve during use, whilestill allowing the collar to be removed when required.

In some embodiments the outer surface of a sleeve or the inner surfaceof a collar may be threaded. This may be done, for example, tofacilitate release of the collar from the sleeve by enabling the collarto be loosened on the sleeve by unwinding the collar with respect to thesleeve.

It may also be useful in situations where additional tightening isdesired to force the collar further over the sleeve, although it isenvisaged that a push may be sufficient in all cases to achieve thenecessary movement of the collar over the sleeve.

A sleeve clamp may also be formed with an elastically deformable sleevewhich may be held open sufficiently by a detail of a locking collar (forexample a tang extending from the inner surface of a collar) to allowthe sleeve to be pushed over a shaft into a fastening position where thesleeve is released to spring onto and clamp against the shaft

In this embodiment an elastically deformable sleeve is pushed partiallyinto a locking collar prior to the sleeve clamp being pushed over ashaft.

The deformable sleeve and locking collar are configured such that as thelocking collar is pushed partially over the sleeve it causes the sleeveto deform so as to increase a perimeter of the sleeve. This action hasthe effect of opening up the sleeve so that the combined sleeve andcollar can be pushed over and along a shaft to the desired position.This may allow the sleeve to pass over any threads or raised detailsthat may be provided as a fail safe mechanism to prevent the collar frommoving back towards a non-engaged position.

The sleeve and collar are further configured such that further pushingof the collar over the sleeve causes the sleeve to revert towards itsundeformed state. The material memory of the sleeve biases it towardreturning to its original shape in which it has a perimeter smaller thanthe shaft. The sleeve is fastened against the shaft by this biasingforce.

In one example of this embodiment an elastically deformable sleeveincludes a slit extending along the length of the sleeve. The slit maybe configured such that it has a narrow internal section having a widthwhich is less than the width of the slit on either side of the narrowsection.

Reference to an internal section of the slit should be understood tomean a section of the slit that does not include an end of the slit.

A locking collar in this embodiment includes a protuberance, which maybe in the form of a tang, on the inner surface of the collar, theprotuberance configured to fit into the slit at an end of the slitwithout touching the sides of the slit.

The protuberance or tang is further configured such that as the collaris pushed along the sleeve the protuberance moves along the slit untilit bears against the sides of the slit on either side of the narrowinternal section,

This action causes the sleeve to be deformed as the slit is widened,thus opening the sleeve sufficiently for the sleeve to be pushed over ashaft.

The sleeve clamp is pushed onto the shaft with the protuberance in thecollar engaged in the narrow section of the slit in the sleeve.

When in position the locking collar is pushed further with respect tothe sleeve such that the protuberance moves away from the narrow sectionof the slit, thus releasing the sleeve to clamp onto the surface of theshaft.

A sleeve clamp according to the current invention provides manyadvantages over the prior art devices. In its simplest form it mayconsist of two pieces only, a deformable sleeve and a locking collar,each of which may be readily formed. Prior art devices generally involvea plurality of interacting parts. This means that the sleeve clamp maybe relatively inexpensive to make.

The pieces do not need to be preassembled, although in some instancesthis may be an advantage. When desired, preassembly requires only thatthe sleeve be pushed into the collar sufficiently for it to befrictionally held in place. No other springs or retainers are required.This is a significant benefit over prior art devices which do usesprings and retainers to locate a plurality of parts, and thereforeinvolve additional costs in materials and assembly.

A major advantage is that a sleeve clamp according to the currentinvention may be pushed over a shaft in order to achieve fullengagement. This contrasts with the prior art fastener devices where thefinal tightening involves rotation of the fastener device after it hasbeen pushed onto a shaft.

A push fit is preferable to a rotation as it is a simpler motion, bothfor hand operation and particularly for automated application by amachine.

For hand operation all that is required is a push on the collar. If moreforce is required than can be simply achieve by hand, this can beapplied by engaging a suitable tool (such as a socket) against thecollar and applying force to the tool, for example by striking with ahammer.

For automated application it is only necessary to have a machine adaptedto hold the collar (with or without the sleeve engaged) and to push thesleeve clamp along the shaft into position, followed by an additionalpush to engage the sleeve clamp on the shaft. This is a much simplermotion for a machine than one involving rotation of a part.

Use of a push fit only means that the operation is quick and simple,saving time, and can be achieved with simple machinery, saving expensein capital investment on more complex machinery.

The use of a push fit only also removes a major limitation of fasteningdevices that require rotation on a screw thread for engagement—namelythat screw threads are limited to objects having a circular crosssection. Hence all threaded bolts, nuts, screws etc are limited tohaving a circular cross section.

Use of a push fit without the need for rotation, as in the basic sleeveclamp of the current invention, opens the opportunity to use objectsthat do not have a circular cross section.

In particular a shaft and sleeve may be used that do not require acircular cross section. Use of a non circular shaft and sleeve (innersurface) provides greater stability to the fastening device againstrotation (as the parts are not able to rotate relative to each other).This may overcome much of the problem associated with vibrationsloosening screwed fasteners.

A sleeve clamp may also be used to advantage to provide a barrier on ashaft, such as may be required to limit the movement of some object pasta point on the shaft. A sleeve clamp may be fastened to a shaft byholding the sleeve in position on the shaft while the collar is pushover the sleeve clamping it to the shaft. In contrast, any fastener thatrelies on a rotation or screwing motion to tighten requires a fixedsurface to tighten against, and therefore cannot be used for thispurpose.

Despite its relatively simple basic form, the sleeve clamp may beconfigured in a multitude of ways to provide additional functionality.These generally involve inexpensive surface modifications of the sleeveand/or collar using conventional machining or forming techniques.Various modifications, as outlined above and illustrated below and incombinations thereof, may be used to tailor a sleeve clamp to therequirements of a particular situation. This option is generally notavailable in prior art devices.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from theensuing description which is given by way of example only and withreference to the accompanying drawings in which:

FIG. 1 shows a fastening device for use with a shaft; and

FIG. 2 shows various embodiments of a sleeve, and

FIG. 3 shows various embodiments of a sleeve, and

FIG. 4 shows a fastening device for use with a shaft, and

FIG. 5 shows a fastening device, and

FIG. 6 shows a fastening device for use with a shaft, and

FIG. 7 shows a fastening device, and

FIG. 8 shows a fastening device.

BEST MODES FOR CARRYING OUT THE INVENTION

A fastening device, generally indicated by (1) in FIG. 1( a), includes adeformable sleeve (2) and a locking collar (3).

The sleeve (2) shown in FIG. 1 has a tapered outer surface (4).

A slit (5) in the form of a cut extends along the length of the sleeve(2).

The slit (5) provides space for the material of the sleeve (2) to moveinto, thus assisting the sleeve (2) to deform when subjected to anapplied radial force (i.e. when squeezed).

The sleeve (2) has a hollow core bounded by an inner surface (6). Theinner surface (6) in the embodiment shown in FIG. 1 is threaded.

The sleeve (2) is configured to cooperate with a threaded shaft (9),shown in FIG. 1 as the shaft of a bolt (10).

The perimeter of the inner surface (6) is such that the sleeve (2) canbe pushed onto and along the shaft (9) into position against an object(11) placed on the shaft (9), as shown in FIG. 1( b). A cut out crosssection of this arrangement is shown in FIG. 1 (e).

The locking collar (3) has a tapered inner surface (7), configured suchthat when engaged with the tapered outer surface (4) of the sleeve (2),the inner surface (7) of the locking collar (3) bears against the outersurface (4) of the sleeve (2), as indicated in FIG. 1 (c).

The locking action is completed by pushing the locking collar (3) overthe sleeve (2). The force applied by the tapered inner surface (7) ofthe locking collar (3) against the tapered outer surface (4) of thesleeve (2) causes the sleeve (2) to deform such that the threaded innersurface (6) engages with the threaded shaft (9), locking the sleeve intoposition on the shaft.

The outer surface (8) of the locking collar (3) is configured into ahexagonal cross-section in order to provide a gripping means, forexample with a conventional spanner (not shown).

In this embodiment the sleeve clamp is tightened if necessary byrotating the locking collar (3) with a spanner. The sleeve (2) andlocking collar (3) are configured such that when fully engaged, as shownin FIG. 1 (d), there is sufficient friction between the outer surface(4) of the sleeve (2) and the inner surface (7) of the locking collar(3) to cause the sleeve (2) to rotate when the collar (3) is turned.

The outer surface (4) and inner surface (6) of a sleeve (2) may bemodified in various ways to meet the requirements of differentapplications. A range of such modifications is shown in FIG. 2. Theseembodiments are shown as illustrations of the type of functionality thatcan be achieved and is not intended to be limiting.

A basic deformable sleeve (12), having a smooth tapered outer surface(4) and a smooth inner surface (6) is shown in FIG. 2(A). The sleeveincludes a slit (5) to facilitate deformation under an applied force.

The inner surface (6) of a sleeve (13) may be threaded (14) as shown inFIG. 2(B).

The cross-sectional shape of the outer surface (4) of a sleeve may benon circular. For example a sleeve (15) having an outer surface with anoval cross-section (16) is shown in FIG. 2(C). The outer surface (4) ofa sleeve may be formed into any convenient shape, such that the oval orcircular cross-sections shown in FIG. 2 should not be seen as limiting.

A sleeve (15) having an oval cross section for the outer surface is usedwith a collar (not shown) having a similar oval shaped cross section forthe inner surface. The oval shape limits or prevents rotation of thecollar with respect to the sleeve (15).

The outer surface of a sleeve (17) may include surface features in theform of a groove (18) as shown in FIG. 3(D), or a plurality of grooves(20, 21 and 22) as shown in the sleeve (19) in FIG. 2(E).

A locking collar for use with sleeves (17, 19) containing a groovedouter surface includes a complementary ridge on the inner surface (7) ofthe locking collar (3). The grooves (20, 21 and 22) may be used toprovide an indication to the user of the extent to which a complementaryridged locking collar (3) has been engaged with a sleeve (17, 19).

Using the sleeve (19) in FIG. 2(E) as an example, a complementarylocking collar is pushed over the narrow end of the sleeve (19) untilthe ridge on the inner surface (7) of the locking collar (3) engageswith the first groove (20) on the sleeve (19). The point at which theridge snaps into the groove provides a clear indication of theengagement of the locking collar (3) with the sleeve (17) at the groove(20).

The pressure exerted by the locking collar (3) on the deformable sleeve(19) is increased by pushing the locking collar (3) along the deformablesleeve until the groove on the inner surface (7) of the locking collar(3) engages with the next groove (21) on the outer surface of thedeformable sleeve (19).

Similarly further force may be exerted by pushing the locking collar (3)further until the ridge on the locking collar engages with the nextgroove (22) on the outer surface of the deformable sleeve (19).

In this embodiment a number of grooves may be formed at variousdistances along the length of the locking sleeve (19) in order toprovide feedback on the extent of engagement on the locking collar (3)over the deformable sleeve (19). This feedback may be sensed by a useras the locking collar (3) is pushed over the sleeve and hence provide anindication of the extent of coverage of the collar on the sleeve (19).

Alternatively, in automated operation, in which a machine is used topush the locking collar (3) over the sleeve (19), a sensor may be usedon the machine to sense when a ridge on the locking collar (3) engageswith each of the one or more grooves on the deformable sleeve (19). Inthis manner, the applied force holding the fastener in place may becalibrated, allowing the machine to be programmed to provide aconsistent, fixed force to the sleeve clamp.

In some embodiments a flange (24) may be included at the base end of thedeformable sleeve (23), the base end being the wider end of the tapereddeformable sleeve (23) that in use abuts the article to be held on ashaft.

A flange (24) may be used to limit further movement of the lockingcollar (3) over the collapsible sleeve (2), as in the embodiment shownin FIG. 2(F). A wider flange (24) is used with some embodiments toprovide a larger surface to bear against an article to be held on theshaft. Such a flange (24) is illustrated in FIG. 2(G).

Note that in each of the previous two embodiments, a slit (25) extendsacross the flange (24).

In some embodiments the outer surface of a deformable sleeve includessurface features in the form of one or more splines (26) or grooves (27)extending the length of the outer surface of the deformable sleeve (28),as illustrated in FIG. 2(H).

A locking collar (not shown) for use with this embodiment is configuredto have matching grooves and splines to engage with the splines (26) andgrooves (27) respectively on the surface of the sleeve (28).

The inclusion of the splines (26) provides a guide for the lockingcollar (3) as it moves along and over the deformable sleeve (28). Thisarrangement locks the locking collar (3) with respect to the deformablesleeve (28), particularly during rotational motion.

This embodiment is particularly useful in applications where a sleeveclamp is used with a threaded shaft (9). In this case the splines (26)and grooves (27) provide a positive locking between the sleeve (28) andthe locking collar (3) when the locking collar (3) is rotated to provideadditional tightening of the sleeve clamp.

The outer surface of a sleeve (29) having surface features in the formof screw threads (30) is illustrated in FIG. 2(I). The locking collarfor this embodiment (not shown) includes a corresponding set ofcomplementary threads. In this embodiment the locking collar is pushedover the sleeve (29) until the threads engage. The threaded section maybe used to loosen off the collar when required by unscrewing the collarwith respect to the sleeve (29). Alternatively, it may be used totighten the collar on the sleeve (29) if required.

A sleeve (31) having an outer surface configured to include a lowernon-tapered section (32) is illustrated in FIG. 2 (J, JJ).

A sleeve (33) having a plurality of slits (34) extending at leastpartially along the length of the sleeve is illustrated in FIG. 2 (K).

A sleeve (34) in which the outer surface is configured in the form of aseries of barbs or ridges (35) is shown in FIG. 3A and in side view inFIG. 3AA. The barbs may be used to provide feedback on the extent towhich a complementary collar (not shown) is pushed over the sleeve (34).

A sleeve (36) in which the outer surface is configured as a screw thread(37) is shown in FIG. 3B and in side view in FIG. 3BB. Use of thissleeve and complementary collar allows additional rotation of the collaron the sleeve in order to provide further tightening if required, orconversely to allow the collar to be unwound from the sleeve (36) inorder to release the sleeve from a shaft (not shown).

A sleeve (38) showing deeper grooves (39) forming a helical screw threadis shown in FIG. 3C and in side view in FIG. 3CC.

A sleeve (40) having a non linear outer tapered surface is shown in FIG.3D and in side view in FIG. 3DD. The engagement of a collar with thesleeve (40) is discussed in more detail below.

It will be appreciated that numerous combinations of the embodimentsillustrated in FIGS. 2 and 3 may be used in a sleeve of the currentinvention,

Another view of a deformable sleeve (2) and locking collar (3) in whichthe inner surface of the sleeve (2) is threaded for attachment to athreaded bolt (9) as shown in FIG. 4A.

A similar arrangement is shown in FIG. 4B in which the inner surface ofthe sleeve (2) and the outer surface of the bolt (41) are not threaded.

FIGS. 4C and 4D show two ways in which a sleeve (2) and a collar (3) ispushed along a shaft (9). In FIG. 4C a sleeve (2) is partially insertedinto a collar (3) to form a sleeve clamp (42) prior to pushing thecombination along a shaft of a bolt (9). The sleeve (2) is held in placein the collar (3) by the force exerted by the elastically deformedsleeve (2) onto the collar (3).

Alternatively, as shown in FIG. 4D the components of a sleeve clamp maybe assembled on a shaft (9) separately. In this case the sleeve (2) ispushed along the shaft (9) prior to the collar (3) being pushed alongthe shaft and over the sleeve (2).

This method of assembly is illustrated in FIG. 4E in which a deformablesleeve (2) is shown after it has been pushed along a shaft (41) andagainst an object (11) loaded onto the shaft (41).

A locking collar (3) is pushed over and along the shaft (41) until theinner surface of the collar (3) contacts the outer surface of the sleeve(2), as illustrated in FIG. 4F.

The clamping action is completed by pushing the locking collar (3)further along the shaft and over the sleeve (2) so that the innersurface of the collar bears down on the outer surface of the sleeve,causing the sleeve to deform and clamp against the shaft (41), asillustrated in FIG. 4G.

FIG. 5A illustrates a sleeve (2) and a collar (3) in which the outersurface of the sleeve (2) and the inner surface of the collar (3) havean oval cross section. FIGS. 5B and 5C show cutaway views of the ovalsleeve (2) and oval collar (3) prior to engagement and partially engagedrespectively.

FIGS. 5D, 5E and 5F show similar views to those of FIGS. 5A to 5C for asleeve (43) and a collar (44) in which the inner and outer surfaces ofthe sleeve and the collar are rectangular.

Both the oval shaped sleeve (2) and collar (3) of FIG. 5A and therectangular shaped sleeve (43) and collar (44) of FIG. 5E illustrateexamples of sleeves and collars which are constrained by their shape tolock together against rotational motion relative to each other.

FIGS. 6A and 6B illustrate the assembly of a sleeve clamp on arectangular shaft (45), the sleeve clamp consisting of a rectangularcross section sleeve (46) and a locking collar (47) having a rectangulartapered inner surface (56) and a cylindrical outer surface (57). FIG. 6Cshows a cutaway view of this arrangement when the sleeve (46) ispartially engaged with the collar (47).

FIG. 6 D illustrates the engagement of a sleeve clamp on a circularshaft (41), the sleeve clamp consisting of a deformable sleeve (48)having an oval shaped outer surface and a corresponding locking collar(41) having an oval shaped inner surface (not shown) and an outersurface (58) configured to accept a spanner. FIG. 6E illustrates acutaway view of the sleeve clamp when partially engaged.

A sleeve clamp in which the outer surface of a deformable sleeve (50) isconfigured in a series of ridges (35), is shown in FIG. 7A and incutaway view partially engaged with a locking collar (51) in FIG. 7B.The inner surface of the locking collar (59) has a complementary shapeto that of the ridges (35) on the outer surface of the sleeve (50), asshown in FIG. 7B.

A sleeve (52), similar to that shown in FIG. 3B, in which the outersurface of the sleeve (52) is threaded is shown in FIG. 7C, andpartially engaged with a locking collar (53) in FIG. 7D. The innersurface of the locking collar (60) has a complementary structure to theouter surface of the sleeve (52).

Engagement of a sleeve (54) having a non linear taper on its outersurface (61) is illustrated partially inserted into a correspondingcollar (55) in FIGS. 8A and 8B, and fully engaged in a perspective viewin FIG. 8C.

FIGS. 8D, 8E and 8F respectively show cutaway views corresponding toFIGS. 8A, 8B and 8C respectively. As can be seen in the cutaway views,the inner surface of the locking collar (55) has a complementary shapeto the outer surface of the deformable sleeve (54).

The circumference of the inner surface of the sleeve reduces as thecollar moves over the sleeve, as clearly illustrated in FIGS. 8D to 8E.

Aspects of the present invention have been described by way of exampleonly and it should be appreciated that modifications and additions maybe made thereto without departing from the scope thereof as defined inthe appended claims.

1. A fastening device for cooperating with a shaft, wherein thefastening device comprises a deformable sleeve; and a locking collar;the deformable sleeve is configured to have a perimeter relative to theshaft such that the deformable sleeve can be pushed over the shaft; andthe locking collar is configured to push over the sleeve so as to bearagainst a surface of the sleeve and to cause the fastening device toengage with the shaft.
 2. The fastening device as claimed in claim 1,wherein the locking collar is further configured to rotate over thesleeve so as to bear against a surface of the sleeve and to cause thefastening device to engage with the shaft.
 3. The fastening device asclaimed in claim 1, wherein the locking collar is configured to pushalong the shaft.
 4. The fastening device as claimed in claim 1, whereinthe shaft is threaded.
 5. The fastening device as claimed in claim 4,wherein the deformable sleeve is configured to engage with the threadsof the shaft when the sleeve is deformed.
 6. The fastening device asclaimed in claim 1, wherein the shaft has a non circular cross section.7. The fastening device as claimed in claim 1, wherein the lockingcollar includes a grip.
 8. The fastening device as claimed in claim 1,wherein the fastening device includes a single sleeve only.
 9. Thefastening device as claimed in claim 1, wherein the sleeve includes aslit extending at least partially along the length of the sleeve. 10.The fastening device as claimed in claim 1, wherein an inner surface ofthe collar and an outer surface of the sleeve are tapered.
 11. Thefastening device as claimed in claim 1, wherein an inner surface of thecollar and an outer surface of the sleeve are frusto-conical.
 12. Thefastening device as claimed in claim 1, wherein the locking collar isconfigured to push over the sleeve so as to bear against an outersurface of the sleeve.
 13. A kit set for a fastening device, comprising:a deformable sleeve; a locking collar; and a shaft, wherein thedeformable sleeve is configured to have a perimeter relative to theshaft such that the deformable sleeve can be pushed over the shaft, andthe locking nut is configured to push over the sleeve so as to bearagainst a surface of the sleeve and to cause the fastening device toengage with the shaft.
 14. A method of using a fastening device inrelation to a shaft, the fastening device including a deformable sleeveand a locking collar, comprising: a) pushing the deformable sleeve intoposition along the shafts; b) pushing the locking collar along the shaftand over the deformable sleeve, so that a surface of the locking collarbears against a surface of the deformable sleeve; and c) pushing thelocking collar further over the deformable sleeve until a surface of thedeformable sleeve fastens to the shaft.
 15. A method of using afastening device in relation to a shaft, the fastening device includinga deformable sleeve and a locking collar, comprising: a) forming afastening device by pushing the deformable sleeve into the lockingcollar until the sleeve is held by the collar; b) pushing the fasteningdevice into position along the shaft; and c) pushing the locking collarfurther over the deformable sleeve until a surface of the deformablesleeve fastens to the shaft.
 16. (canceled)
 17. (canceled)